The present invention relates to dental prosthetics. More particularly, the invention relates to the method and structure for constructing dental models and for supporting the dental models in a manner which replicates normal mouth movements.
Devices intended to support dental models are commonly known in the industry as dental model articulators. These devices have been used for a number of years to construct removable or fixed prosthetic appliances such as dentures, crowns and bridges.
The dental appliances are constructed and adjustments are made before insertion into the patient""s mouth. For example, during construction of a crown, it is desirable to study the crown for compatibility with the patient""s mouth and existing teeth. To accomplish this, the dental models are mounted on a device in a manner which enables the simulation of the patient""s mouth during occlusal and masticatory movement.
Inexpensive disposable articulators currently in use are disclosed in U.S. Pat. Nos. 4,196.518, 4,382,787, 4,449,930, 4,533,323, 4,548,581, and 5,482,460. These articulators incorporate lockable ball-and-socket elements and flexible hinged brackets to mount the upper and lower dental models. When the correct bite relationship is found, the ball-and-socket joints are immobilized with an adhesive. The resiliently flexible bracket and hinge permit simulation of translatory movement, multi-axis pivotal movement, a full range of occlusal and masticatory movements, and other functions. Other U.S. Patents describing articulators include U.S. Pat. Nos. 3,466,750, 4,196,518 and 4,169,314.
However, these articulators, particularly the inexpensive ones, disclosed in U.S. Pat. Nos. 4,548,581 to Huffman and 5,482,460 to Farnor, Jr., have several deficiencies. Once the ball-and-socket joints are fixed with an adhesive, the models cannot be dismounted. Many times remounting is required since the bite record taken in the patient""s mouth is often incorrect. When the mounting is incorrect, these articulators, which do not have any means of remounting, need to be forcefully detached from the models and then be replaced for remounting. This process is cumbersome and time consuming. Another deficiency is that these articulators do not provide a vertical stop. When many teeth are missing or there are no opposing teeth to come into contact with, the upper and lower models collapse. When mounting these kinds of models with articulators that do not have built-in vertical stops, external vertical stops need to be constructed during the impression-pouring process. Another deficiency is that these devices do not provide a self-cleaning mechanism, requiring extensive model trimming and grinding. Yet another deficiency is the numerous steps involved, requiring extensive model work.
The articulator of the present invention provides relative manipulation of dental casts hingedly and yieldingly through full orbital and masticatory ranges wherein every phase and condition of dental occlusive relationships can be accurately portrayed and duplicated. The inexpensive disposable articulator of present invention was made possible by the built-in design and novel features which eliminate many steps and manual operations, increasing both productivity and quality dramatically.
The articulator of the present invention consists of three partsxe2x80x94a lower frame, an upper frame, and a middle frame. The lower frame is comprised of an elongated rectangular box, a deformable bracket, and a snap-fit male hinge. The upper frame is comprised of an elongated, channeled surface, a deformable bracket, a snap-fit female hinge, and a platform with holes. The middle frame is in the shape of a picture frame, which is snap-seated on top of the elongated box in the lower frame.
The lower frame is for the master dental cast in which the teeth under restoration reside. The elongated box in the lower frame has an open bottom and an insert at the top. The outer surface of the insert bears a series of functional grooves. The imprints of the grooves are copied onto the bottom of the cast when the model stone is poured. With these imprints, the dies made out of the master cast can return to their original positions. In the middle of the platform at the front end of the lower frame is a hole to hold a plastic bar which adjusts the vertical height of the jaws.
The snap-fit hinge provides pivotal movement around a pivot axis. The hinge in the present invention is made of two componentsxe2x80x94a male and a female component. The two components are not mirror images of each other.
The upper frame is for mounting the opposing dental cast. The bottom (inner) surface of the upper frame is divided into two different areas. Along the middle of the frame is a flat area with a slotted opening. This flat area can be used to attach a pre-prepared cast with an adhesive. Outside of the flat area are two rectangular boxes, one on each side. These boxes are provided so that the model stone can be poured onto the surface to mount the opposing cast. Some of the poured stone enters the slotted opening and locks the cast onto the frame. The platform at the front end of the upper frame has three holes. With a plastic bar in place in one of the three holes, the upper and lower casts are maintained at the original vertical height of the jaws even when all of the patient""s teeth are missing on the cast. The L-shaped deformable bracket supports the hinge assembly. The horizontal section of the bracket may be softened by heating for quick bite correction and remounting.
The middle frame is for removing any excess model stone and increasing the master model thickness by the height of the frame. When the middle frame is seated on top of the elongated box, a rectangular box is formed. A master cast is made and mounted when this rectangular box is filled with the model stone and the impression is placed on top of the box, with all spaces in between filled with stone.
By incorporating all of the above advantages in the design, the present invention yields superior model work with regards to quality, accuracy, workmanship and productivity. The imprinted grooves on the bottom of the master cast yield greater accuracy over the conventional grooves made with an instrument by hand. No prior art disposable articulators feature built-in vertical stops, nor do they have a built-in feature for quick remounting. No prior art disposable articulators have the versatility to accommodate any type of impression trays, whether the impressions are already poured or not. All of these features contribute to the quality of the present invention.
Important requirements of a disposable articulator include cost, productivity, quality, remountability, the presence of vertical stops, and versatility.
Accordingly, the primary objective of the present invention is to provide an improved disposable articulator.
Another objective of the present invention is to be able to accommodate all single-sided, double-sided, quadrant-arch, half-arch, or full-arch impression trays. It accommodates unpoured impression trays (wet) as well as poured casts (dry).
Yet another objective of the present invention is to provide an articulator with a means of correcting the mounting quickly.
Still another objective of the present invention is to incorporate a built-in vertical stop.
A further objective of the present invention is to provide a means of adjusting the vertical height.
Yet a further objective of the present invention is to reduce working time, therefore increasing productivity.
Still a further objective of the present invention is to provide an articulator with a self-cleaning mechanism which eliminates the need for model trimming and grinding, dramatically increasing productivity.
An additional objective of the present invention is to provide an articulator that yields accuracy of the crowns.
Another objective of the present invention is to yield quality workmanship and aesthetics.
Still another objective of the present invention is to provide an articulator which automatically puts grooves on the bottom of the master cast, eliminating the need for hand-grooving.
A further objective of the present invention is to provide an articulator which automatically exposes the pins.
Yet a further objective of the present invention is to provide an articulator with an improved method of assembling and disassembling dental models.
Still a further objective of the present invention is to provide an articulator which is simple, inexpensive and disposable.